This application is a 371 of PCT/JP00/00525.
The present invention relates to a packed battery wherein a plurality of single cells are combined and joined together so that they can be handled more easily as a single battery of a predetermined shape with certain voltage required for respective applications.
Battery has its own specified voltage value that differs corresponding to the type of battery. Similarly, the size of battery, as well as dischargeable current value and electric capacity, are defined for each type of batteries. It is, however, often the case that the voltage and current values that are required for certain applications are different from those of a battery available on the market. It is thus customary practice to connect a plurality of batteries in series or in parallel so as to obtain voltage or current of required value.
Packed battery, that has been developed for the purpose of simplifying the handling of a plurality of batteries used in combination as described above, enables a plurality of batteries to be used as a single battery in accordance with various applications by joining them together in a predetermined shape, and has been widespread in recent years. Such packed battery is disclosed, for example, in Japanese Unexamined Published Patent Application No. 10-69892.
FIG. 23 is an exploded perspective view of such packed battery. Two cells 1, 2 such as nickel-cadmium battery are disposed in close contact with each other with their respective longitudinal axes parallel to each other and with their respective positive and negative terminals arranged opposite from each other. The positive terminal and the negative terminal that are adjacent with each other at one end of these cells 1, 2 are electrically connected with a positive temperature coefficient (PTC) element 3, while input/output terminals 4, 7 are respectively attached to the positive terminal and the negative terminal juxtaposed at the other end of the cells 1, 2. The two cells 1, 2 that are thus connected to each other are then united by means of a frame body 10 comprising an upper end plate 8 and a lower end plate 9. That is, by bringing each of retaining plates 11, 12 into contact with both ends of the two cells 1, 2 in a lengthwise direction, the distal ends of support pieces 13, 14 provided in pairs respectively to both of the end plates 8, 9 are abutted with each other, and this abutted portion of the two pairs of support pieces 13, 14 are joined together by ultrasonic welding. The two cells 1, 2 are thus united in a state of being sandwiched between both retaining plates 11, 12 of the integrated frame body 10.
The input/output terminals 4, 7 attached respectively to each of the united cells 1, 2 are exposed to the outside through windows 17, 18 formed in the upper end plate 8 for being electrically connected to outside terminals. A labeling sheet 19 is then wrapped around and bonded to the peripheries of the respective cells 1, 2 united by the frame body 10, thereby completing the packed battery. The packed battery constituted as described above is highly durable against vibration or shock as compared to a packed battery that is merely covered with a label consisting of a heat-shrinkable synthetic resin tube with a lead connector connected to the cells. Furthermore, it has an advantage over a packed battery that is housed in a casing of synthetic resin in that it is small-sized, light-weighted, and inexpensive.
However, the packed battery described above has a large number of components, and its assemblage involves complicated processes such as abutting the distal ends of the respective pairs of support pieces 13, 14 formed in the separate upper and lower end plates 8, 9 of the frame body 10 and bonding them by ultrasonic welding. The number of assembling steps is large and the cost is high accordingly. Furthermore, in case there is variation in length or other features of each support piece 13, 14 in the above described packed battery, these support pieces 13, 14 will be connected to each other in a misaligned state. If this happens, the two cells 1, 2 cannot be united at predetermined relative positions without any play therebetween. The yield of packed batteries may thus be decreased.
Apart from the above, the packed battery described above has the following drawback. As long as the packed batteries such as the one described above are produced solely for a specific purpose in which the number of cells 1, 2 to be connected and the way in which they are packed together are limited to one type of packed battery, no inconvenience will arise. However, if several types of packed batteries that have the same appearance but different specifications such as output voltage are fabricated by, for example, connecting two lithium cells in series and in parallel and sold, needs will arise for providing features for distinguishing one type of battery from another and for preventing misuse of the packed battery. The above-described packed battery is given no consideration for preventing complications in this regard.
In the case of manufacturing and selling several types of packed battery, it is necessary to indicate the differences in specifications such as output voltage of the battery by some characters or designs. Moreover, the packed battery should have a construction such as to prevent a user from using a packed battery of wrong specification by mistake, or such as to make the user realize the mistake immediately so that an electric appliance for which the packed battery is used will not be damaged.
Specifically, if a packed battery with a specification of 6V output voltage in which two lithium cells of 3V terminal voltage are connected in series is used by mistake for an electric appliance for which a packed battery with a specification of 3V output voltage in which the cells are connected in parallel should be used as a power source, it is quite likely that the electric appliance is damaged. Thus the packed battery must be provided with a construction that never fails to prevent such misuse. On the other hand, if a packed battery of 3V output voltage is used for an appliance that requires 6V voltage as a power source, the appliance cannot fully perform its function, and therefore, the packed battery must also have such features as to make the user of the battery to realize that the battery is a wrong type and should not be used in the appliance the user wishes to use.
With the above described problems in prior art in view, an object of the present invention is to provide a packed battery that can be manufactured in a predetermined shape in a high yield at a low cost by reducing the number of components and the number of assembling process steps, and that is provided with features for preventing misuse between packed batteries of different specifications or reverse connection of the packed battery.
In order to achieve the above objects, the present invention according to one aspect thereof provides a packed battery comprising a plurality of cells joined together in series- or parallel-connection and arranged with their axes parallel to each other and their external surfaces in proximity to or in contact with each other, and with their juxtaposed electrode terminals electrically connected to each other at least at one end with a connector piece. A frame body into which said cells are mounted includes a pair of first and second end face covers that respectively cover the entire surface of end faces of the adjacent cells at both ends, a connecting bar for connecting said pair of end face covers opposed to each other at a space corresponding to a length of the cells, and a retaining piece that is shorter than the connecting bar and is provided to the first end face cover to protrude parallel to the connecting bar, all of which end face covers, connecting bar, and retaining piece are formed in one piece. The cells are held at their lengthwise ends by the end face covers and at their widthwise sides by the connecting bar and the retaining piece, thereby being retained in the frame body.
In this packed battery, since the frame body is formed in one piece, the number of components is reduced as compared to the frame body of a conventional packed battery. Furthermore, a plurality of cells that are joined together can be mounted into the frame body by one-touch operation utilizing resiliency of one end face cover and the retaining piece provided thereto, i.e., since no complicated processes such as welding while positioning both cells are required, the number of assembling process is reduced, and the production cost is accordingly decreased. Moreover, since the frame body is molded in one piece and its configuration is defined uniformly by the molding, no variation occurs in configuration unlike in the conventional frame body that is assembled by connecting several components. The cells can thus be held at predetermined positions in relation to each other and joined together in the frame body without any play, whereby the yield of the packed battery can be increased.
Preferably, the first end face cover should have a thin portion in which the connector piece attached to one end of the cells fits in, and the second end face cover should have a plurality of terminal windows for allowing the electrode terminals of the cells to be exposed to the outside. Further, both of the connecting bar and the retaining piece should have a cross section such that they can fit in a concavity between the adjacent cells, and the retaining piece should have a length ⅓ to xc2xd of the connecting bar. By the presence of the thin portion, the first end face cover exhibits resiliency and allows the retaining piece to readily deform, whereby the cells joined together can be smoothly mounted into the frame body.
It is preferable that the first end face cover be formed ellipsoidal in shape while the second end face cover be formed substantially in the shape of letter B having a dent in conformity with the external shape of one end of the cells joined together. Further, the dent should have a depth that varies corresponding to an output voltage specification of the packed battery. Misuse of packed batteries of different specifications can thereby be prevented by providing a corresponding guide rail that matches the depth of the dent in the end face cover to a battery holder of an electric appliance in which the packed battery is used. For example, troubles such as damage to electric appliance caused by misuse of a 6V packed battery in an electric appliance that requires 3V drive power source can be prevented.
In the above described packed battery, the retaining piece may also have a length that varies corresponding to an output voltage specification of the packed battery. By providing a corresponding guide rail that matches the length of the retaining piece to a battery holder of an electric appliance in which the packed battery is used, the retaining piece can prevent insertion of a wrong packed battery by abutting the distal end of the guide rail in the battery holder.
The above described packed battery may be constituted such that all of the cells are arranged in a same direction with their positive terminals juxtaposed and electrically connected to each other by a positive connector piece welded to the positive terminals, and with their negative terminals electrically connected to each other by a negative connector piece welded to the negative terminals, an insulating tape is affixed on the positive connector piece, and a positive terminal piece that is electrically connected to the positive connector piece and a negative terminal piece having a same thickness as that of the positive terminal piece and being electrically connected to the negative connector piece through an interconnecting member are bonded on the insulating tape affixed on the positive connector piece. With this arrangement, while the cells are arranged all in the same direction and connected in parallel, the positive terminal and negative terminal of the cells can be arranged on an identical plane at one end of the cells. Since this configuration defines the direction of insertion, the packed battery allows itself to be readily exchanged by a user while being a parallel-connection packed battery.
Specifically, the positive terminal piece is integrally formed to the positive connector piece such as to be bendable relative to the positive connector piece, while the negative terminal piece communicates with the negative connector piece through the interconnecting member such that the interconnecting member extends from the negative connector piece in an orthogonal direction and the negative terminal piece is continuously formed to the distal end of the interconnecting member such as to be bendable relative thereto. The positive terminal piece and the negative terminal piece are respectively bent so as to be bonded on the insulating tape that is affixed on the positive connector piece. The packed battery wherein the cells are connected in parallel, while the positive and negative terminals are arranged on the identical side can thereby be assembled with a reduced number of components.
It is preferable that an adhesive be applied to both sides of the insulating tape in advance, so that both of the terminal pieces can readily be positioned and bonded at predetermined locations.
It is also possible to construct the above described packed battery such that the cells are arranged in opposite directions. In this case, connector pieces of a positive terminal connecting member are respectively welded to each of the positive terminals of the cells for electrically connecting them. These connector pieces are provided to both ends of an interconnecting line in electrical contact therewith. Meanwhile, a negative terminal connecting member is welded at both ends to the negative terminals of each of the cells. Thereby, while the cells are arranged in opposite directions and connected in parallel, the positive terminal and negative terminal of the cells can be arranged on an identical plane at one end of the cells. Since this configuration defines the direction of insertion, the packed battery allows itself to be readily exchanged by a user while being a parallel-connection packed battery.
The above described packed battery can also be constituted such that the cells are not covered with an outer tube, and the both ends of the negative terminal connecting member are welded to the exterior surface of the cell casing of each cell. Thereby, unfinished cells in a normal cell production process can be used to produce packed batteries, thus decreasing the cost further.
In the above described packed battery, a heat-sensitive or heat-shrinkable outer label may be wound around and bonded to the exterior surface of the cells and the frame body except a part from the distal end of the retaining piece in the first end face cover to the second end face cover. An indentation formed between the adjacent cells can be thereby utilized in combination with the guide rail in the battery holder of the electric appliance as the features for distinguishing packed batteries of different specifications, i.e., the guide rail is guided along the indentation formed between the cells, and prevents insertion of a wrong battery by abutting the distal end of the retaining piece.
It is also possible to constitute the above described packed battery such that the frame body includes a first support piece integrally formed to the distal end of the retaining piece of the first end face cover such as to be stepped and thinner than the retaining piece so as to fit in a concavity between the adjacent cells. Further, a second support piece is integrally formed to the second end face cover opposite the first support piece such as to fit in the concavity between the adjacent cells. A heat-sensitive or heat-shrinkable outer label is wound around and bonded to the entire exterior surface of the cells and the frame body. The outer label is formed with slits so that it fits to the exterior shape of the cells and that a portion of the outer label corresponding to a part of the cells from the distal end of the retaining piece in the first end face cover to the second end face cover is supported by the first support piece and the second support piece. While the cells and the frame body can be securely joined together by wrapping the outer label around the entire exterior surface thereof, an indentation can be formed between the first and second support pieces, whereby packed batteries of different specifications are distinguished from one another.
Alternatively, first outer label of heat-shrinkable material may be wound around and bonded to the exterior surface of the cells and the frame body except a part from the distal end of the retaining piece in the first end face cover to the second end face cover, and a second outer label of non-heat-shrinkable material may be wound around and bonded to the part from the distal end of the retaining piece in the first end face cover to the second end face cover. Thereby, since the second outer label does not deform even in a high temperature atmosphere, the indentation that is formed in a portion where the second outer label is bonded can be maintained. Apart from the above, if a material that shrinks at a predetermined temperature is used for the second outer label, it can be used as a temperature sensor of the packed battery, whereby a packed battery that has been exposed to a predetermined temperature atmosphere can be detected.
The packed battery according to a second aspect of the present invention comprises a plurality of cells joined together in series- or parallel-connection and arranged with their axes parallel to each other and their external surfaces in proximity to or in contact with each other, and with their juxtaposed electrode terminals electrically connected to each other at least at one end with a connector piece. A cell casing into which said cells are mounted includes a pair of first and second end face covers that respectively cover the entire surface of end faces of the adjacent cells at both ends, a bottom wall that connects said pair of end face covers opposed to each other at a space corresponding to a length of the cells, and a partition boss projected on the bottom wall along a lengthwise direction thereof, all of which end face covers, bottom wall, and partition boss are formed in one piece. The cells are placed upon the bottom wall along the partition boss and held at their lengthwise ends by the end face covers, thereby being retained in the cell casing.
In this packed battery, since the cell casing is formed in one piece, the number of components is reduced as compared to a conventional packed battery. Furthermore, a plurality of cells that are joined together can be mounted into the cell casing simply by inserting them from above, the number of assembling process is reduced, and the production cost is accordingly decreased. Moreover, since the cell casing is molded in one piece and its configuration is defined uniformly by the molding, no variation occurs in configuration unlike in the conventional frame body that is assembled by connecting several components. The cells can thus be held at predetermined positions in relation to each other and joined together in the cell casing without any play, whereby the yield of the packed battery can be increased.
The second end face cover of the above described packed battery should preferably have a plurality of terminal windows for allowing electrode terminals of the cells to be exposed to the outside, and the partition boss should preferably have a cross section such that it can fit in a concavity between the adjacent cells, whereby a plurality of cells can be stably held in the cell casing.
The above described packed battery may be constituted such that the first end face cover is formed substantially in the shape of letter B having a dent in conformity with the external shape of one end of the cells joined together, the dent having a depth that varies corresponding to an output voltage specification of the packed battery, while the second end face cover is formed substantially in the shape of letter D, and both of the end face covers have one linear side where they are connected with each other through the bottom wall, said linear side of the end face covers being formed with square projections at both ends thereof. In combination with a corresponding guide rail that matches the depth of the dent and that may be provided to the battery holder of an electric appliance in which this packed battery is used, misuse of a wrong packed battery can be prevented. By forming the opening shape of the battery insertion hole of the battery holder in conformity with the square projections of the end face covers, it can be made certain that misuse of a wrong packed battery is prevented.
It is also possible to constitute the above described packed battery such that the cells are arranged in opposite directions, circular terminal plates of identical shape are respectively welded to the electrode terminals juxtaposed to each other at one end of the cells at locations offset from the center of the cells, while the electrode terminals juxtaposed to each other at the other end of the cells are electrically connected with each other by a connector piece welded thereto, and the second end face cover of the cell casing has non-circular terminal windows formed therein at locations opposite each of the circular terminal plates. The use of identical terminal plate for both of the positive and negative terminals of the cells in fabrication of series-connection packed batteries reduces material cost, as well as increases the speed of welding operation, since the circular terminal plate needs not be positioned in a certain direction.
In the above described packed battery, a partition piece may be integrally formed between the terminal windows, whereby the adjacent terminal plates or electrode terminals are prevented from being short-circuited by a metal piece or the like during fabrication process.
The above described packed battery may also employ the construction wherein a heat-sensitive or heat-shrinkable outer label is wound around and bonded to the entire exterior surface of the cells and the cell casing, whereby the cells and the cell casing can be securely joined together.